1. Field of the Invention
The invention relates to an automation device and method for operating the automation device, which includes a CPU module that is configured to effect read or write access to local peripherals that are each provided with two interface modules that are each wired up in ring form to an input/output controller, where peripheral access operations are executed via one of the rings or via both rings, and where a redundancy manager that is provided for each ring is used to logically interrupt the respective ring in a normal mode and to initiate ring reconfiguration for this ring in the event of a physical ring interruption.
2. Description of the Related Art
Methods and automation devices are known in the field of automation engineering, and to increase the availability of the communication link between the input/output controllers (I/O controllers) of an automation unit and the local peripheral units (local peripheral, I/O devices), the link is of redundant design, and a media redundancy protocol (MRP) is also provided. In normal mode, the respective redundancy manager or respective MRP manager logically interrupts the respective ring, where the redundancy manager is able to form part of the respective input/output controller and has two interfaces (two ports) for data transmission. The logical ring interruption prevents the information transmitted from the CPU module of the automation unit to the peripheral units, e.g., messages, packets or data, from looping in the respective ring, such as on account of an erroneous peripheral address. This means that the respective ring wiring logically represents a linear structure based on the respective ring interruption.
It may now arise that between two peripheral units, for example, one of the ring wiring elements is physically interrupted or one of the peripheral units has failed, and therefore the redundancy manager is no longer able to receive the test information supplied to the ring via one port at its other port. In this case, the redundancy manager initiates reconfiguration of the communication path by indicating the changed topology or the changed linear structure to the peripheral units. The redundancy manager then uses both interfaces or uses both ports to transmit the information, which means that the information is transmitted in opposite directions. During what is known as a dead time, which represents the period of this ring reconfiguration or the period of the “training” with respect to the new linear structure, the CPU module is unable to effect read or write access to the peripheral units, which has a disruptive effect on the control of a technical process that needs to be controlled.